Biodiesel is a processed fuel that can be derived from biological sources such as refined plant oils. Biodiesel can be utilized alone or mixed with conventional petroleum-based diesel for use in most standard diesel engines. Biodiesel can also be utilized as a heating fuel in commercial and domestic boilers.
Biodiesel can be considered an environmentally friendly alternative to petroleum-based fossil fuels. For example, use of biodiesel can result in an overall reduction in greenhouse gas emissions and can be produced domestically, resulting in a lower dependence on fossil fuel imports.
Biodiesel can contain one or more long-chain fatty acid alkyl esters, including, but not limited to, fatty acid methyl esters, fatty acid ethyl esters, fatty acid propyl esters and fatty acid isopropyl esters formed from a transesterification or esterification reaction. Fatty acid alkyl esters can be created from the transesterification of triglycerides present in plant oil feedstocks and/or animal fat feedstocks. Fatty acid alkyl esters can also be created from the esterification of free fatty acids present in acidified soap stocks. The conversion to fatty acid alkyl esters can be produced by catalyzed or uncatalyzed reactions.
Soap stocks can be obtained as a byproduct of crude vegetable oil refining performed to remove undesired components from the triglyceride fraction of the oils.